1. Field of the Invention
The invention relates to an inking device.
2. Discussion of the Prior Art
German reference DE 295 10 929 U1 discloses a printing group with a short inker that has an inking device of this type in a rotary printing machine. The inking device contains a blade device which supplies printing ink to a structured ink transfer roller.
Other blades that serve to remove excess printing ink from the surface of a roller with depressions, especially cups, are also known, e.g., chamber blades. In inking devices of this type, frictional heat is produced by friction between the blade and the roller on which the blade rests. This heat partially dissipates into the structured roller, e.g., a cup roller, but in part dissipates into the printing ink itself. A smaller portion dissipates via the blade into the blade holder and from there into the printing machine frame.
It has been found that the heat flow in the blade is hindered primarily by the small cross-sectional area of the blade, relative to the main direction of the heat flow. The result is that the blade tip becomes highly heated. Therefore, the printing ink in contact with the blade, as well as the cup roller, heats up in the region of the outer circumference of the roller.
In all printing processes, particularly flat-bed printing and, especially, water-free flat-bed printing, a constant temperature is required to ensure consistent and adequate print quality.
For this reason, one or more of the rollers or cylinders in the inking device may be cooled. At times, the form cylinder is cooled as well. The disadvantage of such cooling is that when a cooling liquid is supplied to a rotating body, i.e., a roller or cylinder, rotations must be carried out. Furthermore, other cooling methods, such as blowing cool air onto the mantle surfaces of the rollers or cylinders, are relatively ineffective. In particular, the quantity of heat that develops in the blade tip is already distributed to a large mass, so that the temperature difference between the cooling medium and the mantle surface of the rollers and cylinders is much lower than the temperature difference between the blade tip and the media surrounding the blade tip. When the temperature difference is low, the cooling expense is high, i.e., a great deal of coolant must be supplied for a relatively long period to achieve a relatively small decrease in temperature.